กก
The sound-absorbing performance of the
two-component sound-absorbing cotton material is related to its
structure, weight (thickness), depth of specimen tube
and the geometrical structure parameters and physical parameters such as
the use environment, so the above-mentioned factors are analyzed. Figure
1 for the
two-component sound-absorbing cotton material microstructure, shaped
like a fine cotton cocoon, the internal fluffy a large number of gaps,
the gap is more
evenly distributed within the material is staggered through each other,
the gap open to the outside world, The sound waves are easy to enter
into the gap.
1. Influence of Material Thickness on Acoustic Property Fig. 1 shows the
effect of material thickness on the acoustic properties of different
thicknesses
(5mm, 10mm, 18mm, 23mm, 24mm) and weight (100g / m2, 200g / m2, 300g /
m2,400g / m2, The sound - absorbing coefficient of the sound - absorbing
cotton.
(G / m2) Thickness 18mm400 (g / m2) Thickness 23mm420 (g / m2) Thickness
24mm Figure 1 The thickness of different thickness and the thickness of
the film
thickness of 10mm300 (g / m2) Sound absorption coefficient curve of the
weight of material From Figure 1 shows, five different thickness and
weight of sound
-absorbing performance curves are parabolic, indicating that with the
material thickness and weight increase, sound-absorbing performance is
also increasing,
which the thickness of 24mm, weight 420g / m2 when the intermediate
frequency sound absorption coefficient of the highest value in the high
frequency, the
five models have shown a clear and stable sound-absorbing performance,
to 2000 Hz after the high-frequency section, a gentle trend, which shows
The structure
of two-component sound-absorbing cotton material in the high-frequency
band showed good sound-absorbing performance. Figure 2 for different
thickness and
weight of two-component sound-absorbing cotton material sound insulation
test results.
With the increase of thickness, the sound insulation performance in the
low frequency band, the overall trend is still showing an increase, but
the noise
fluctuations in the curve is more obvious, especially in the vicinity of
high-frequency 3150Hz, there is a large trough, The sound insulation
performance of
the material is poor at this point and the sound insulation performance
curve value is not stable at the high frequency stage. It is proved that
the sound
insulation performance of the multi-component sound-absorbing cotton
material is enhanced with the increase of thickness in a certain
frequency band , But
when the thickness exceeds a certain critical value, the sound-absorbing
noise-reducing performance will be weakened with the increase of the
thickness.
Generally speaking, the sound insulation performance of the
two-component sound-absorbing cotton material has a certain relation
with the thickness and the
grammage; under the same structure, it can show the better acoustics
effect between thickness and weight. 2. Effect of tube depth on acoustic
performanceFig.3 is the sound absorption coefficient of two-component
sound-absorbing cotton material with thickness of 18mm and weight of
300g / m2 at
different tube depths (0mm, 3mm, 6mm, 9mm, 13mm) Test Results
The results show that the curves of different depths have different
characteristics. When the tube depth is 0mm, the frequency curves of
each point show a
gradual increase. When the depth of the specimen tube is 3mm and 6mm,
the test results are parabolic , And the highest value appeared in the
middle frequency
band. When the depth of the test tube was 9mm and 13mm, the test results
were wavy and linear, and the highest value appeared at the low
frequency. The
lowest value appeared at 1250Hz ~ 1600Hz, It is shown that the sound
absorption coefficient of the low-intermediate frequency band is
superior to that of the
high frequency band except for the tube depth of 0 mm. Which in 2000Hz
after the high frequency band shows relatively stable values, the depth
of the tube is
not sensitive to the specimen. Therefore, increasing the depth of the
specimen tube, can greatly improve the low-frequency sound absorption
coefficient,
which is equivalent to increasing the thickness of the sample, but
reduced the intermediate frequency sound absorption coefficient, the
impact of high
frequency is not too great. Therefore, we can see that the depth of the
sample tube has a greater impact on the sound absorption coefficient.
Figure 4 is the
thickness of 18mm, weight 300g / m2, different tube depth of the
specimen (0mm, 20mm, 40mm) under the sound insulation
With the increase of the depth of the specimen tube, the low-frequency
sound-insulating performance of the material is little affected, and the
regularity of
the sound-insulating performance curve in the middle frequency band to
the high frequency band is weakened, and the fluctuation of the curve is
obvious.
Which in 2000Hz after the high frequency sound absorption coefficient
values ??tend to focus, showing a relatively stable value, we can see
that the noise
performance of the test tube is not sensitive to the depth. Which
indicates that the two-component sound-absorbing cotton material has
good sound-absorbing
and noise-reducing effect. The space behind the material plays an
important role in increasing the thickness of the material, which is
equivalent to
improving the fluffy effect of the material, so the sound-absorbing
property of the material is much better than that of the material. Also
changed,
especially the low-frequency part of the sound-absorbing performance. In
addition, when the sound waves into the empty tube of the sample, the
air can
stimulate the air resonance resonance increased losses, which can
improve the material sound-absorbing effect. This provides a reference
for the two-
component sound-absorbing cotton material in vehicle assembly design and
practical application, location layout and so on. 3. Effect of ambient
temperature
on acoustic properties Fig. 5 shows the sound absorption coefficient of
different components (200g / m2, 300g / m2, 400g / m2) of
multi-component sound-
absorbing cotton under different test conditions (temperature, humidity)
result.
The results of the whole curve show that the low frequency to
intermediate frequency show an increasing trend, the change trend of the
intermediate frequency
band is relatively stable, and the trend to the high frequency zone is
gentle. With the increase of temperature and humidity, the sound
absorption
coefficient of the low frequency has no obvious change; The results show
that the experimental results show that the acoustic properties of the
multicomponent sound-absorbing cotton material are in good agreement
with the experimental data (temperature and humidity). Have a certain
impact, the
overall impact is not obvious..
กก